Polymeric ultraviolet light stabilizers prepared from phenol formaldehyde condensates

ABSTRACT

THIS INVENTION RELATES TO POLYMERIC ULTRAVIOLET LIGHT STABILIZERS WHICH ARE THE ESTERIFICATION PRODUCTS OF (A) PHENOL-FORMALDEHYDE CONDENSATES, WHICH HAVE AT LEAST 12.5 MOL PERCENT OF THE POSITIONS ORTHO TO THE ESTERIFIABLE HYDROXY GROUP UNSUBSTITUTED, AND (B) A COMPOUND CAPABLE OF ESTERIFICATION WITH PHENOL FORMALDEHYDE CONDENSATE WHICH CONTAINS AT LEAST ONE RING OF SIX CARBON ATOMS CHARACTERIZED BY HAVING BENZENOID UNSATURATION. UPON EXPOSURE TO ULTRAVIOLET LIGHT, THE EXPOSED PORTION OF THE ESTER REARRANGES TO FORM A POLYMERIC COMPOUND WHICH IS A BARRIER TO ULTRAVIOLET LIGHT.

United States Patent Oflice 3,817,924 Patented June 18, 1974 POLYMERICULTRAVIOLET LIGHT STABILIZERS PREPARED FROM PHENOL FORMALDEHYDECONDENSATES Raymond H. Young, Jr., Macon, Ga., and Albert H. Markhart,Wilbraham, and Joseph G. Martins, Ludlow, Mass., assignors to MonsantoCompany, St. Louis, M0.

N Drawing. Continuation-impart of applications Ser. No. 849,210, Aug.11, 1969, now Patent No. 3,650,799, and Ser. No. 606,595, Jan. 3, 1967,now abandoned. This application Feb. 11, 1972, Ser. No. 225,653

Int. Cl. C08g 5/06 US. Cl. 260-59 6 Claims ABSTRACT OF THE DISCLOSURECROSS-REFERENCES TO RELATED APPLICATIONS This application is acontinuation-in-part of copending application Ser. No. 849,210, filedAug. 11, 1969, now US. Pat. 3,650,799, and application Ser. No. 606,595,filed Jan. 3, 1967, and now abandoned.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates to polymeric compositions capable of absorbing ultraviolet lightand acting as a barrier to ultraviolet light. More particularly, thepresent invention relates to aromatic compounds which will undergorearrangement in the presence of ultraviolet light to form a compoundwhich is stable to and will act as a barrier to ultraviolet light.

Description of the prior art Ultraviolet light is that portion of thespectrum just beyond violet on the short wave length side, generallyfrom 180-390 mg. Ultraviolet light is emitted by the sun, carbon arclamps, mercury vapor lamps, tungsten arc lamps and other light sources.The invisible rays from the ultraviolet region induce chemical activitywhich is both beneficial and adverse. Some of the adverse effects ofultraviolet light are degradation of synthetic resins, such as polyvinylchloride which is commonly used in exterior structures and articlesexposed to sunlight such as sidings, awning and the like; discolorationof the resinous interlayers used in architectual laminates; fading anddeterioration of cellulosic materials such as wood, paper, and the like;fading of black and white and colored photographic prints; fading anddiscoloration of paints, etc. Indeed, the full list of adverse effectsof ultraviolet light is too numerous to be set forth here.

Some aromatic polyester compositions currently available aiford somepartial degree of protection from ultraviolet light. However, thesematerials are inadequate by virtue of the fact that they are not opaqueto ultraviolet light in the 300-400 my region or more likely, theythemselves are subject to ultraviolet light degradation.

Other ultraviolet light stable aromatic polyesters such as described inUS. Pat. 3,234,167 are relatively stable to ultraviolet light. However,these polymers do not necessarily act as ultraviolet light barrierswhich would serve to protect other less stable materials intimatelyassociated with the ultraviolet light stabilizers.

Monomeric type ultraviolet light stabilizers, while providing a certaindegree of protection from the adverse effects of ultraviolet light,exhibit serious drawbacks which preclude their widespread use. Examplesof these drawbacks include non-film forming properties, stabilizermigration, stabilizer extraction, poor mechanical stability, etc.

A definite need exists for polymeric ultraviolet light stabilizers withlittle or no tendency to migrate or be extracted and which will provideexcellent protection from and act as a barrier to ultraviolet light.

SUMMARY OF THE INVENTION The present invention is directed to aromaticpolymeric ultraviolet light stabilizers which are the esterificationreaction product of (A) a phenol formaldehyde condensate, having atleast 12.5 mol percent of the positions ortho to the esterifiablehydroxyl groups unsubstituted, and (B) a compound capable ofesterification with the hydroxyl groups on the phenol formaldehydecondensate, which compound contains at least one ring of 6 carbon atomscharacterized by having benzenoid unsaturation. Upon exposure toultraviolet light the exposed portion of the polymer rearranges to forma polymeric ultraviolet light stabilizer which is also a barrier toultraviolet light. The un-- exposed portions of the polymer do notrearrange and are available for rearrangement at a later time when theyare exposed to ultraviolet light.

The present invention solves problems previously existent in the priorart by providing; a polymeric material which affords an excellentbarrier to ultraviolet light. Moreover, this material has little or notendency to migrate or to be extracted.

The preparation of the polymeric ultraviolet light stabilizers of thisinvention and their subsequent rearrangement may be represented by thefollowing general formulae:

Formula I Formula II 3;. i1. 11. t t .5

Formula (III)-Rearrangeable Polymer Upon exposure to ultraviolet lightthe exposed portions of the rearrangeable ester shown in Formula IIIabove will rearrange to form a material which may be represented by thefollowing general structure:

t t-.. l. l.

Formula IVRearranged Polymer It is this latter structure which possessesthe ultraviolet light barrier properties which characterize the novelpolymers of this invention.

Thus, after exposure to UV light, films of the polymeric materialscomprise two superposed contiguous layers. The outer exposed layer,which is the rearranged polymer, has a structure corresponding to thatshown in Formula IV above. The inner unexposed layer, which is therearrangeable polymer, has a structure corresponding to that shown inFormula HI above. Thus, the ultraviolet light exposed polymers of thepresent invention are copolymeric in nature, wherein the rearrangeableesters (Formula IH) form one repeating unit while the ultraviolet lightrearranged polymer (Formula IV) is the other repeating unit.

DESCRIPTION OF THE PREFERRED EMBODHVIENTS The polymeric backbones usedin the preparation of the polymeric ultraviolet light stabilizers ofthis invention are phenol formaldehyde condensates of the novolac orresole type. These may be generally represented by the followingstructural formula:

a RE 1 RH CH CH2 LR Jn R Formula I wherein n is an integer of from 1 to25 and R is selected from the group consisting of hydrogen, halogen, aradical of from 1 to 18 carbon atoms selected from the group consistingof alkyl, alkenyl, haloalkyl, and alkoxy, a radical of from 5 to 18carbon atoms selected from the group consisting of cycloalkyl,cycloalkenyl, alkylcycloalkyl, halocycloalkyl and cycloalkyloxy, and aradical of from 6 to 18 carbon atoms selected from the group consistingof aryl, alkaryl, alkenylaryl, alkylhaloaryl and aryloxy. Exemplary ofsuch radicals are methyl, octadecyl, ethenyl, octadecenyl, hexadecenyl,2-chloroethyl, methoxy, octadecyloxy, cyclopentyl, cyclopentenyl,dicyclopentenyl, decylcyclohexyl, chlorocyclohexyl, cyclohexyloxy,phenyl, nonylphenyl, phenylethyl, methylphenylethyl, indanyl,bromophenyl and phenoxy. The R groups may be in the meta or paraposition so long as there are at least 12.5 mol percent of the positionsortho to the esterifiable hydroxyl groups available, i.e.,unsubstituted. Mixtures of phenols can be used in the preparation of thephenol formaldehyde condensate so that the aromatic rings may not all besubstituted, or the substtiuents may differ from ring to ring.Preferably, n is an integer of from 2 to 20 tion of this type reactionis notoriously well known in the art and needs -no further discussionhere. The nature of this invention requires that the structurerepresented by Formula III must have at least 12.5 mol percent of thepositions ortho to the esterified hydroxyl group available, i.e.,

unsubstituted in order for the rearrangement to take place.

Preferably, there should be 16% mol percent and more preferably 20 molpercent of available ortho positions.

iamino, sulfone amidefsul-fonylchloride, etc,--=

When there are less than 12.5 molpercent available ortho positions,there will be limited or no rearrangement of the esterification product(Formula IH) to form the ultraviolet light absorbing compoundsrepresented by Formula IV. In such a case, where there are from 1.85 toless than 12.5 mol percent of positions ortho to the hydroxylgroup-available, undesirably large amounts ofthe compounds representedby Formula IV are'required to provide the necessary level of ultravioletlight stability.

The polymeric ultraviolet light stabilizers: of i-this' invention areprepared by esterifying the hydroxy gronpsin Formula I with acompound'which correspondsto'the folxii-it, v (Formula II) wherein R isa monovalent radical containing at least one ring of six carbon atoms,saidringcharacterized by benzenoid unsaturation wherein the benezenoidring is attached directly to the carbonyl group; and'wherein X isselected from the group consisting of halogen, hydroxyl, ester groupscharacterized. by the structure R gy a d anhydride groups characterizedby the structure.

. 99 wherein R is selected from the group connistingof aliphaticradicals of from -1 to ,5 carbon atoms and aromatic radicals of from 6to8 carbon atoms. 1

The nature of the X constituent in FormulaII is such that it must becapable of esterification with the hydroxyl groups in Formula I. Thismaybe conveniently carried out by the straight forward esterificationreaction of the hydroxyl groups with an acid halide, free acid or acidanhydride group. An alternate method'which mayb'e'used, when X is analkoxy group such as Ri- O -jis the well known transesterificationtechnique. The preferred' X group ishalogen.

An essential requirement for theR group in Formula II is that itcontains at least one'ring of six'carbon atoms characterized bybenzenoid runsaturation which is com nected directly to the wherein R isa divalent radical selected from the group consisting of aliphaticraricals of from 1 'to'4 carbon atoms, oxygen, sulfur, sulfonyl,phosphonyl and 'silanes such as Si(R wherein R4 iS- an aliphatic radicalof from 1 to 4 carbon atoms.-w=

' -It should be noted further that the examples of suitable R groups setforth above may also contain' ring'su-bstituents in the ortho;'meta andpara positionsfiExamp'les of these ring substituents'would includealiphatic'radicals and alkoxy radicals wherein the aliphaticand-alkylgroups contain from 1 to 4"carbon atoms,-halogen", nitro' *dimethyl 'Itshould be noted that it is not necessary to este'rify all of thehydroxyl groups in the phenol forinaldehdye'condensates (Formula I) "in'order to prepare polymers with good ultraviolet light barrierproperties. The concept of this invention contemplates having arearrangeable poly mer (Formula III) which contains from to 20% and morepreferably 0l5% residual hydroxyl groups. It should be noted that anyunesterified phenol, hydroxy groups or methylol end groups may alsoserve as crosslinking sites if a crosslinked structure is desired.

The relative amounts of reactants as represented for Formulae I and IIthat will be required to produce a given polymer will depend upon theparticular systems used and the desired degree of residual hydroxylgroups in the rearrangeable polymer (Formula III). This concept ofcontrolling the amount of reactants in order to control the finalpolymeric composition is well known to those skilled in the art and willbe further illustrated in the working examples.

The following examples are set forth to further illustrate reactantswhich are represented by Formula II above and are contemplated for usein the practice of this invention.

Acid halides such as benzoyl chloride, benzoyl bromide,p-methoxy-benzoyl chloride, p-chlorobenzoyl chloride, mnitrobenzoylchloride, p-amino-sulfonyl benzoyl chloride, 3,5-dibromobenzoylchloride, 4-chlorocarbonyl biphenyl, 4-chlorocarbonyl diphenyl ether,p-(phenyldimethyl silyl) benzoyl chloride, 3,4-methylenedioxy benzoylchloride, p-

(methylthio)benzoyl chloride, etc. Free acids such as benzoic acid,p-methoxy benzoic, p-toluic acid, p- (4-phenyl-n-butyl)benzoic acid,p-phenyl benzoic acid, paminosulfonyl benzoic acid, as well as the freeacids of the foregoing acid halides.

Acid anhydrides such as p-nitro benzoic anhydride, pchloro benzoicanhydride, benzoic acetic mixed anhydride, benzoic trifluoroacetic mixedanhydride, etc.

Esters which are capable of undergoing a transesterification reactionsuch as methyl p-dimethylamino benzoate, methyl 3,5-dimethyl benzoate,phenyl benzoate, phenyl pbenzoyl benzoate, phenyl p-dimethylaminobenzoate, etc. The esters prepared from aromatic type alcohols arepreferred.

The following examples are set forth in illustration of this inventionand should not be construed as being limitations thereof. All parts andpercentages are by weight unless otherwise indicated.

PART I Preparation of the polymeric ultraviolet light stabilizersEXAMPLE 1 This example illustrates the use of a solution process toprepare a polymeric ultraviolet light stabilizer. The reaction iscarried out in a one liter resin flask equipped with a stirrer,condenser, thermometer and dropping funnel using the followingmaterials.

Charge A:

100 g. phenolic novolac 135 g. benzoyl chloride 500 ml. tetrahydrofuranCharge B:

100 g. triethylamine Charge A is placed in the flask and is cooled to 8C. with an ice-water bath. The phenolic novolac resin used is a phenolformaldehyde condensate of the type represented by Formula I havingapproximately 50 mol percent available ortho positions and wherein R ishydrogen and n is 8. Charge B is then added over a 45-minute period fromthe dropping funnel. A precipitate of triethylamine hydrochloride formswithin 2 minutes indicating that the esterification reaction is takingplace. When the addition is complete, the ice-water bath is removed andthe reaction mixture is allowed to warm to room temperature. Stirring iscontinued for 3 hours followed by filtration of the slurry. The clearfiltrate is disintegrated in water and the ester filtered. The resin iswashed with water twice and once with methanol and then once again withwater. The product is air-dried at room temperature.

Yield of the nearly white solid is 189 g. which is of the theoreticalyield. An additional 3-6 g. is isolated from the triethylaminehydrochloride which is removed before distintegration. Analysis of theresin indicates less than 5% residual hydroxy groups: indicating almostcomplete esterification.

EXAMPLE 2 This example is set forth to illustrate one of the manypossible variations that may be made in the nature of the R group inFormula II.

Example 1 is repeated here except that 164 grams of pmethoxybenzoylchloride is used in place of the benzoyl chloride used in Example 1. Thepolymeric product which is recovered in a yield of about 94% oftheoretical, contains less than 5% residual hydroxy groups, and iscomparable to the product obtained in Example 1.

EXAMPLE 3 This example illustrates the preparation of the polymericultraviolet light stabilizers of this invention using an interfacialpolymerization process.

The reaction is carried out in a one liter resin flask equipped with apaddle stirrer, gas inlet condenser, thermometer and dropping funnelusing the following materials:

Charge A:

54 g. phenolic novolac 22.8 g. sodium hydroxide 300 ml. water 3 g.Duponol ME surfactant Charge B:

80 g. benzoyl chloride Charge A is placed in the flask and cooled withan icewater bath to 10 C. The phenolic novolac resin used is a phenolformaldehyde condensate of the type represented by Formula I having 60%available ortho positions wherein R is hydrogen and n is about 4.Nitrogen is bubbled through the solution for 10 minutes and then ChargeB is added to the rapidly stirred solution over a period of 20 minutes.Within 4 minutes the esterified product be gins to precipitate. When theaddition is complete, the color of the solid precipitate is light yellowand the mixture is basic to pH paper. However, an additional 15 minutesof stirring completes the reaction and the mixture becomes neutral to pHpaper. The resin is filtered and washed twice with water, once withmethanol, and finally once again with water. The slightly tan resin isair-dried at room temperature.

The yield of resin is 91 g. (86% of theory). Analysis shows a residualhydroxy content of 13 EXAMPLE 4 This example is set forth to illustratea method for lowering the residual hydroxyl content of the polymericproduct. Example 3 is repeated here except that grams of benzoylchloride is used instead of the 80 gram quantity used in Example 3. Theresultant. polymeric product, recovered in a yield which is 93% oftheoretical, has a residual hydroxyl content of about 2% EXAMPLE 5 Thisexample is set forth to illustrate another of the many possiblevariations that may be made in the nature of the R group in Formula H.

Example 3 is repeated here except that 144 grams of para nitrobenzoylchloride dissolved in 300 ml. methylene chloride is used in place of thebenzoyl chloride used in Example 3. The polymeric product, 'which isrecovered by disintegration in methanol in a yield of about 94% oftheoretical, contains less than residual hydroxy r'on 5s,--a iscomparable to the 'product obtained in Example ll" f V I EXAMPLE 6 Thisexample is set forth to'illu'strate a variation in the solutionesterification technique using an inorganic acid acceptor in place ofthe triethylamine acceptor used in Example 1. The following ingredientsare charged to the same apparatus used in Example '1:

Charge: 100g. phenolic novolac 185 g. m-nitrobenzoyl chloride 400 ml.acetone 145 g. potassium carbonate (anhydrous) The phenolic novolacresin used is a phenol formaldehyde condensate of the type representedby Formula I This example is set forth to illustrate the use of acompound represented by the general Formula II wherein X represents ananhydride structure.

The esterification reaction is carried out using a 500 ml. resin flaskequipped with a stirrer, condenser and thermometer. 10.0 grams of thephenolformaldehyde condensate ued in Example 1 is added to 100 ml. ofanhydrous pyridine in the flask while maintaining continuous agitation.The fiask is cooled with a water bath maintained at room temperature(2527 C.) 28.6 grams of para-chlorobenzoic anhydride is added to theflask over a 15 minute period. The initially dark solution of reactantsbecomes virtually colorless after 1 hour of mild agitation. The reactionmixture is then poured into 2 liters of water in a high shear blenderwhile maintaining vigorous agitation. Solid sodium bicarbonate is addedto the blender until the aqueous phase becomes slightly basic at whichtime the aqueous phase is decanted and the solid resin is washed withwater, methanol and then again with warm water (6070 C.). The whiteresin which has a residual hydroxyl content of 6.2% is dried overnightat 50 C. in a circulating air oven, to yield 21.8 grams of polymericproduct.

EXAMPLE 8 This example is set forth to illustrate the preparation of thenovel polymeric ultraviolet light stabilizers of this invention using areactant which corresponds to the general structure of Formula IIwherein X is a hydroxyl p- Y I The esterification reaction is carriedout in the appara- -tus used in Example 3 wherein 10.5 grams of thephenol formaldehyde condensate used in Example 6 is reacted with 19.8grams of para phenyl benzoic acid. The reactants are charged to theflask and a nitrogen purge is maintained for 15 minutes after which time162 grams The slightly yellow resin which has a residual hydroxylcontent of 17.6% was obtained in a 71% yield.

H EXAMPLE 9 I The following example is set forth toillustrate-the .useof a compound corresponding .to the general structu ral Formula 11wherein -X is an ester group andalso 'to illustrate thetransesterification reaction used in the preparation of the polymericultraviolet light-stabilizers of. this invention. Into the apparatusdescribed in Example-7 is charged 25.4 grams of phenyl p-benzoylbenzoate and.10.5 grams of the phenol formaldehyde condensate, used inExample 1. The solid reactants are heated to about 70 Cabeforeliquifaction takes place, at which time .1 gram of magnesium metal isadded. The reaction mixture isheatedfor 6 hours during which time thephenol formed frorntransesterification is distilled ofl? over atemperature range of from to C. under 1.5 mm. pressure. The solidresidue in the flask is triturated with acetone and poured into water.The tan polymeric product which contains about 10% residual hydroxylgroups is washed three times with water and twice with methanol. Yieldis 18.8 grams.

JEXAMPLE 10 The following example is set forth to illustrate thepreparation of a polymer having only 11.1 mol percent available orthopositions and the subsequent inefliciency of this polymer as anultraviolet light stabilizer. The phenol formaldehyde condensate usedhas noterminal methylol groups and is prepared exclusively frompara-cresol wherein the formaldehyde condensation reaction is directedto the ortho positions. The resulting condensate has 11.1 mol percent ofortho positions available and corresponds to the general structuralFormula I wherein Ris methyl and n is 7. 11.8 gramsof this material isreacted with 14 grams of benzoyl chloride according to the procedurefollowed in Example 6. The resulting polymer was found to contain about7% residual hydroxyl groups. As will be illustrated in the test beow,the insufficient number" of available ortho positions limit theability'-'of "this compound to rearrange to form suitable ultravioletlight barriers of the type represented by Formula IV. I i

EXAMPLE 11 Example 10 is repeated except that the degree of condensationof the phenol formaldheyde resin is.regulated so that n=6 to give acondensate with 12.5 mol percent of available ortho positions. The testsbelow will illustrate the improved efficiency of the ultraviolet lightbarrier properties of the rearranged form of this compound when comparedto that prepared in Example 10.

EXAMPLE 12 Example 10 is repeated except that the degree of condensationof the phenol formaldehyde resin is regulated so that 11:4 to give acondensate with only 16 /3 mol percent of available ortho positions. Thetests below will illustrate the improved efficiency of theultravioletlight barrier properties of the rearranged form of thiscompound when compared to that prepared in Example 10.

EXAMPLE 13 light stabilizer, which inability is presumed to bedue. to

the unsaturated vinyl structure which is interposed, between thecarbonyl group and the benzenoid ring.

The following examples, set forth in tabular form, further illustratessome of the possible variation in the nature of the reactants that maybe used in the practice of this invention. The solution procedure ofExample 1 is followed here, the weight ratio of the respectivestructures Formula H/Formula I was varied from a 0.5 to 2.0/1. In eachinstance a rearrangeable polymeric ultraviolet light stabilizer wasobtained.

3 Bromine The esterification techniques set forth in the foregoingexamples are generally well known to those skilled in the art and needno further explanation here.

PART II Rearrangement and testing of the polymeric ultraviolet lightstabilizer The rearrangeable polymeric compounds represented by FormulaHI are prepared in Part I are tested further here in order to illustratethe ability of that portion of the polymer which is exposed toultraviolet light to rearrange to a structure represented by Formula IV.It is these rearranged structures which provide the barriers toultraviolet light.

In the following tests, the rearrangeable polymeric materials preparedin Examples 1-13 are incorporated into a poly(vinyl butyral) resin bydissolving the resin and the rearrangeable polymeric materials in asuitable solvent. About one part of rearrangeable ester is used perhundred parts of resin (phr.). The solution is then cast and the solventevaporated to form films about 0.4 mil thick. The films are then exposedto ultraviolet light according to the procedure outlined below.

The ultraviolet lamp used for irradiation is a Hanovia 450-watt lightpressure quartz mercury-vapor lamp, model 679A with a reflector, whichis positioned about 25 cm. from the sample. The approximate intensity ofall ultraviolet radiation (200-400 m reaching the sample isapproximately 1.1 microwatts/cmF. The total output of ultravioletradiation from the lamp is 83.7 watts which represented 47.5% of thetotal radiation emitted, the remaining 52.5% consisting of visible andinfrared radiation. For the sake of comparison it should be noted thatthe intensity of the ultraviolet light radiation of sunlight is onlyabout 10-300 microwatts/cmF.

Spectra of the films are obtained using a Beckman DK-2 Spectrophotometerover the wavelength range of approximately 500 to 240 millimicrons. Therearrangeable esters represented by Formula II'I initially aretransparent to ultraviolet light in the 300-400 m range; whereas, therearranged hydroxybenzophenone structures represented by Formula IV havea strong absorption band 20. Hydrogen..

10 at about 350 mg. Thus, the increase in absorption along with theformation of the band at about 345 millimicrons upon exposing toultraviolet light corresponds to the formation of characteristica-hydroxybenzophenone groups. These groups are formed as the esters(Formula III) rearrange to the structure represented in Formula IV.

The poly(vinyl butyral) does not absorb ultraviolet light in the 300-400m wave length range used in the test. Thus, all absorption of theultraviolet light rays is due to the polymeric ultraviolet lightstabilizers prepared in Part I above.

The time required for the esters represented by Formula III to rearrangeinto a--hydr0xybenzophenone structures represented by Formula IV andbecome effective stabilizers is dependent on such variables as theintensity of ultraviolet light incident on the sample, the concentrationof the rearrangeable ester in the polymer and the type of polymer thesubstituents present in the acid portion, and the number of availableortho positions. Table 1 gives the times necessary, under the conditionsstated above, to obtain approximately 50% rearrangement.

TABLE 2.IRRADIATION TESTS ON POLY(VINYL BUTYRAL) CONTAINING POLYMERICULTRAVIOLET LIGHT STABILIZERS 1 Example numbers refer to the polymericstabilizer prepared in the foregoing Working examples.

This value indicates the percentage of ultraviolet light absorbed atmaximum absorption.

5 In Examples 2-9, the tests were discontinued after 60 hours.

4 No absorption.

The superior results obtained when using the polymeric ultraviolet lightstabilizers of Examples 1-9 and 11-12 illustrates the excellentultraviolet light barrier properties imparted 'by the polymericstabilizers prepared in accordance with the teachings of this invention.The relatively poorer ultraviolet light stabiilty observed when usingthe stabilizer prepared in Example 10 illustrates the need for having atleast 12.5 mol percent available ortho positions in order to allowsutficient rearrangement to take place to form the necessary ultravioletlight stabilizing structure (Formula II). Example 13 illustrates theneed to have the benzenoid ring attached to the carbonyl group in theFormula H type reactants.

A comparison of the results obtained when using the polymericstabilizers of Examples 10 to 12 illustrates that some degree ofprotection is obtained when using materials that have as little as 11.1mol percent available ortho positions. However, the amount of protectionob tained falls 01f rapidly as the number of available ortho positionsapproaches zero. Note that the stabilizer prepared in Example II having12.5 mol percent of available ortho positions gives about 72% moreexposure time than the stabilizer of Example 10, whereas the stabilizerof Example 12 having 16% mol percent of available ortho positions givessignificantly better protection for longer exposure times.

The following data are presented to illustrate the elfect of ultravioletlight exposure times on the ultraviolet light percent transmission ofthe irradiated sample. In these examples polyvinyl butyral of the typeused above and :11 a rearran'geable p'olymer prepar'eddn Part Iaboveare'dis- "'solve'd in' a so'lvent. The resulting solution containsfrom abburOIS to 1.0 parts" rearrangeable-polymeraper:hundred'partsofresini*'" a Films of 'varying thicknessesare cast .on glasspanes" and their air dried to give clear, colorless; t1--ansparent.films. The films are then irradiated with ultraviolet light accordingtdthe procedures setforth above, forgiven periods :of' time. The spectraof the'film are then obtained ori'a Bezlr'niziriD102-Spectrophotometerover the .wavelength range of approximately 500 [lift-240 m In somecases 's pectraa're obtained using 'no reference and "some using anunirradiated film as a reference.

Within one minute of irradiation by the 450 watt ultraviolet lamp anoticeable increase in absorption occurs around 345 my and around 265 muwhen unirradiated film is used in reference holder. However, as theirradition continued, the amount of increase in absorption at thesewavelengths became progressively smaller and eventually no significantincrease is observed. The following tables show this effect .TABLE3.-U.V. IRRADIATION OF THE REARRANGEABLE POLYMER PREPARED IN EXAMPLE 1AND RESULTING Film thickness 1 0.6 mil 0.9 mil 1.3 mil Time (minutes) 1Percent T 3 1 Exposure time of films to ultraviolet light source. 1Concentration of rearrangeable polymer is 0.5 parts per hundred partsleSlXl. 'I=Pereent transmission at Amaximum=345 millimicrons (m Note thedecreasing amount of percent T with increasing UV. irradiation time andincreasing film thickness.

In the following Table 4 the data given are for a 0.3 mil film ofpolyvinylbutyal which contains 1.0 parts per hundred parts ofpolyvinylbutyral of the rearrangeable polymer prepared in Example 3above. In this series an unirradiated film is used as a reference whichgives rise to the band at 265 mp 'Note the decreasing amount of percentT with increasing U.V. irradiation time which is comparable to thatreported in Table 1.

TABLE 4.--U.V. IRRADIATION OF THE REARRANGEABLE POLYMER PREPARED INEXAMPLE 1 AND RESULTING PERCENT TRANSMISSION OF U.V. LIGHT USING ANUNIRRADIATED REFERENCE v 1 Percent transmissloii'at X ma1dmum=345millimicrons. Percent transmission at X maximum=265 millimic'rons.

. :QThe experiment reported in Table 4 isirepea ted in the followingTable 5 except that no referencefilm is used. .,.-The.following valuesare obtained.

'arrange'd'pjor tion acts as a b'arrier to ultraviolet: 1g

.the number-of absorbing species presentin 'the.1ight .,pa th. Thisnumber can be altered-either by, varying the concen- 7 ,trationof theabsorbing molecules or by varying theth'ick- Percent T 345 m Note thatafter the sample had been irradiated for 480 minutes only a very slightchange in percent transmission occurs upon further irradiation of thefilm.

In the following Tables 6 and 7, the data presented is ultraviolet lightirradiation exposure times *and theresulting ultraviolet light percenttransmission for the rearrangeable polymers. prepared in Examples 2 and5 above. The experimental procedures used are the same as those used inobtaining the data in Tables 3 and 4. In each Table the irradiatedsample was a 0.3 mil film of polyvinylbutyral which contains 1.0 partsof rearrangeable polymer per hundred parts of polyvinylbutyral.

- TABLE 6 UV irradiation of the rearra-ngeable polymer prepared inExample II and. resulting percent transmission of UV light Percent:transmission at 'maximum.'3,40*milllmicrons.

' TABLET I 'fl UV irradiation of the rearrangeable polymer prepared 'inExample 5 and resulting percent transmissionof UV Time (minutes): IPerent T 1 5 p i 951.7 35 v A 71.3 65.0 59.5 480 51.7 1800 50.2

Percent transmission at A max'lmumt3 48 'millimiei ons. The slight shiftin the wavelength-for). maximum in Tables 6 and 7 is believed to be dueto thei's'ubst itu'ent para-methoxybenzoate and para nitro group's foundin these polymers. As in Table 3 and 4 above, increasing 'times ofultraviolet light irradiation results in decreased ultraviolet lighttransmission. This indicates that asit'he irradiated portion of 'thepolymer rearranges the reht protecting the unexposed portidrpj'Thus, theunexposed portion is still in th'e unrearranged' form. A U

The above tables show the effect olf increased irradiationonpolyvinylbutyral films containing the li -earra'ngeable polymers of the presentinveptiom'namely, the leveling of thepercent Tineach case.

The absorption offli'ghtliby molecules, is depende' 13 ness of theabsorbing sample. These are combined into one expression calledBeer-Lambert Law which is expressed as follows:

log =ECL (constant) (concentration) (cell length) The term is called theabsorbance A, thus A=ECL.

A consideration of this law will enable those skilled in the art tocalculate the amount of rearranged polymer that is present in theultraviolet light irradiated polymers of this invention. In the aboveexpression E is called the extinction coefiicient and may have any unitsdesired. Usually, when working with monomeric compounds of knownmolecular weight, the concentration is given in moles per liter and thethickness in centimeters which leads to B being called the molarextinction coefiicient. When the molecular weight of a polymeric sampleis unknown, the concentration is given usually in terms of grams/literor some other appropriate number. A useful value for E when working withunknown compounds is to use the term K value which is defined as thatamount of material (in grams) dissolved in a liter of solution whichreduces the incident light to of its orginial value. Therefore, sinceT=10%, T=0.10 and l/T=10;

and

thus the K value can be expressed When calculating the percentrearrangement the quantities C and L are then given in terms ofgrams/liter (g./l.) and centimeters (cm.). If we assume the polyvinylbutyral to have a density of 1.0, the concentration of the unrearrangedpolymer becomes 5-10 g./l., and the film thickness is converted tocentimeters.

The K value for the films given in the above Tables, are calculated at atime when the rearrangement is essentially unalfected by furtherirradiation. The theoretical K values for the polymers of the presentinvention is taken at 54.5. This K value is determined by applying theprinciples of the Beer-Lambert law to the percent transmission valueobserved in Table 4 above after the sample is irradiated for 120minutes. The above K value correlates well with the K values reported inthe literature for the monomeric analogs.

TABLE 8.CALOULATION OF PERCENT REARRANGE- MENT WHICH OCOURS INULTRAVIOLET LIGHT IRRA- DIATED POLYMER SAMPLES 1 Refers to sample shownin above tables.

Ultraviolet light irradiation time for samples expressed in minutes.

5 Concentration of rean-angaable polymer in polyvinyl butyral expressedin parts per hundred parts of resin.

4 Thickness of irradiated sample in mils.

5 Percent T Percent transmission ofultravioldet light at wavelengthsshown in above tables.

Percent of rearrangeable polymer that has undergone rearrangement underthe stated conditions.

Note that in the foregoing Table 8 the percent rearrangement varies from8 to 100%. These values in Table 8 vary according to the sample exposuretime, concentration of rearrangeable polymer initially present, and

sample thickness. The rearranged material represents a homopolymer ofthe orthohydroxybenzophenone structure represented by Formula IV above.Conversely, the unrearranged starting material is a rearrangeablehomopolymer corresponding to the structure represented in Formula IIIabove. The partially rearranged materials contain a reservoir ofunrearranged polymer which is capable of undergoing rearrangement uponexposure to ultraviolet light.

It should be noted, that in order to obtain a polymeric material whichcomprises two superposed contiguous layers comprising (1) an outerexposed layer which is a rearranged polymer represented by the generalstructure of Formula IV above; and (2) an inner unexposed layer which isan unrearranged polymer of the type represented by Formula III above,the thickness of the unrearranged starting material should be at least0.5 mils. This requirement will be readily apparent to those skilled inthe art in view of the above discussion of the Beer-Lambert law.

From the data set forth above, it should be readily apparent to thoseskilled in the art that a wide variety of useful compositions may beprepared according to the teachings of the present invention. Thesecompositions comprise a polymer comprising:

(A) from 1 to 99 mol percent of the following recurring unit:

R1 t=o @CHa-; and

l. J (B) from 99 to 1 mol percent of the following recurring unit:

wherein R is selected from the group consisting of hydrogen, halogen andaliphatic radicals of from 1 to 5 carbon atoms and wherein R is amonovalent radical containing at least one ring of six carbon atoms,said ring characterized by benzenoid unsaturation and attached directlyto the carbonyl group.

The following Examples 21-25 are set forth to further illustrate thesuperior ultraviolet light stability imparted by the polymericstabilizers of this invention.

EXAMPLE 21 One part of the polymeric stabilizer prepared in Example 1 ismilled into 100 parts of a standard p0ly(vinyl chloride) formulation andthe composition is extruded into unpigmented, translucent 60 milsheets-of the type commonly used in exterior applications in buildingconstruction. This material, along with a control sample which containsno polymeric ultraviolet light stabilizers, is then exposed toultraviolet light under accelerated conditions. After 100 hours, thecontrol sample has deteriorated badly whereas the sample containing thepolymeric stabilizer of Example 1 is relatively unchanged after 650hours.

EXAMPLE 22 Example 21 is repeated here except that polystyrene is usedin place of the polyvinyl chloride used in Example 21. One hundred partsof polystyrene is stabilized with 0.50 parts of the stabilizer preparedin Example 1, while a control sample is prepared with no stabilizer.

vUpon exposure to ultraviolet light the control panel isbadly-discolored within 50 hours whereas the stabilized panel showsonlyslight change even after 200 hours. W-ExamplesZl to 22 are repeatedusing the polymeric stabilizers prepared in Examples 2 to 13. When usingthe stabilizers. prepared in Examples 2 to 9, and 11 to 12, resultscomparable v.to those obtained in Examples 2i to '22 are obtained.However, when the esterification product of Example 13 is used, noultraviolet light stabilization is achieved and little or no dilferenceis observed between the control panel and that containing the additive.When using the esterification product of Example 10, some protection isachieved but not at the level provided by the 'stabilizers of Examples 1to 9 and 11 to 12.

The polymeric light stabilizers of this invention may also be used incertain situations as protective coatings for various substrates as isillustrated by the following Examples 23-24.

EXAMPLE 23 One half of a white pigmented poly(vinyl chloride) panel iscoated with a 15% methyl ethyl ketone solution of the polymericultraviolet light stabilizer prepared in Example 3. The solvent isevaporated depositing a 035 mil film on the panel which is then exposedto ultraviolet light. The unprotected, uncoated portion of the panelbecomes dark after 24 hours whereas the coated protected portion showsno visual change in the substrate.

EXAMPLE 24 One-half of a white pigmented poly(vinyl chloride) sheet iscoated with a thin film of poly(vinyl butyral) containing 1.0 p.h.r. ofthe polymeric light stabilizer prepared in Example 5. After 100 hours ofirradiation the protected portion was virtually uneifected while theunprotected portion had turned dark within 24 hours.

EXAMPLE 25 EXAMPLE 26 This example is set forth to illustrate one of themany possible variations that may be made in the nature of the R groupin Formula (1).

Example 1 is repeated except that in place of the unsubstituted phenolicnovolac a phenolic novolac prepared by condensing formaldehyde withphenol, 20 mol percent of which is substituted with phenylethyl groupsby alkylation with styrene under Friedel-Crafts conditions is used. 120grams of this modified phenolic novolac wherein n is 8 and-there'isapproximately 40 mol percent available 'ortho positions, is reacted with135 g. benzoyl chloride.

The polymeric product which is recovered in a yield of about 90% oftheoretical, contains less than residual "hydroxy groups. The product ismore flexible than the product of Example 1.

'This invention contemplates using the polymeric ultraviolet stabilizersprepared therein as additives to materials to be protected, as films orcoatings to be applied to substrates, or as additives to film formingmaterials which may be used per se or subsequently applied as films andcoatings to protect various materials or substrates.

The materials that may be protected by the polymeric ultraviolet lightstabilizers of this invention are wide and diverse. Indeed thesestabilizers find use wherever protection from the adverse etrectsofultraviolet lightis 'desired. The polymeric ultraviolet light.stabilizers-of this invention may be used to protect thermoplasticpolyvinyl plastics such as polyvinyl chloride, styrene,methylmethacrylate and other related polymers. As is well known. tothose skilled in the art these materials find widespread use in exteriorarchitectural applications such as sidings, rain gutters, awnings, etc.,which are commonly used in building construction; in molded vehicleparts such as stop light lenses, .dashboar'ds, seat "covers; in lawn andgarden furniture, globes for navigation lights, etc.

The polymeric ultraviolet light stabilizers oft'h tion also findwidespread use as additives to paints, varnishes, strip coatings,primers and other related coatiii'g materials. They may also be used toprotect te'x'tilesg fabrics, paperboard materials, metal and wood. i

The amount of polymeric ultraviolet light stabilizerto be used in anygiven application will depend on such factors as (a) the degree ofprotection desired, (b) the type of application, e.g., use as anadditive, as a coating, or

as an additive to a coating, (c) the thickness of the pro tectivecoating (d) the incidence and intensity of the ultraviolet light to beexpected in the given application, (e) the nature of the material to beprotected, etc.

As indicated in Example 22 excellent protection isobtained using aslittle as 0.5 parts per hundred 'partsof resin of the polymericstabilizers prepared in Examples 1 to 6 as an additive in polystyrene.Similarly, one mil'film overlays containing polymeric stabilizers'atlevels as low as 0.5 parts per hunted parts of resins give comparablygood protection to coated substrates. The upper limit on the amount ofstabilizer used will vary with the intended application and the natureof the system. In the case where films of the polymeric stabilizersof'this'invention, are used (Examples 23-24) excellent protection isachieved using films as thin as 0.5 mil.

In view of the foregoing, it should be obvious that many variations arepossible within the scope and practice of this invention withoutdeparting from" the spirit and scope therein. v

What is claimed is:

1. A composition of matter which comprises'a polymer comprising: v

(A) from 1 to 99 mol percent of the following recurring unit:

(B) from 99 to 1 mol percent of the following {recurwherein the totalnumber of recurring units ils between 1 and 25; wherein the end groupsare:

wherein R is selected from the group consisting of hydrogen, halogen, aradical of from 1 to 18 carbon atoms selected from the group consistingof alkyl, alkenyl, haloalkyl, and alkoxy, a radical of from 5 to 18carbon atoms selected from the group consisting ing of cycloalkyl,cycloalkenyl, alkylcycloalkyl, halocycloalkyl and cycloalkyloxy, and aradical of from 6 to 18 carbon atoms seected from the group consistingof aryl, alkaryl, alkenylaryl, aralkyl, haloaryl and aryloxy; wherein Ris a monovalent radical containing at least one ring of six carbonatoms, said ring characterized by benzenoid unsaturation and attacheddirectly to the carbonyl group; and wherein at least 12.5 mole percentof the positions ortho to the groups are unsubstituted. 2. Thecomposition of claim l'wherein R is hydrogen. 3. The composition ofclaim 1 wherein R is an unsubstituted benzene nucleus.

4. The composition of claim 1 wherein R is hydrogen and R is asubsituted benzene nucleus.

5. The composition of claim 1 wherein the R radical is selected from thegroup consisting of:

wherein R is a divalent radical selected from the group consisting ofaliphatic radicals of from 1 to 4 carbon atoms, oxygen, sulfur,sulfonyl, phosphonyl and wherein R is an aliphatic radical from 1 to 4carbon atoms and wherein the R radical is unsubstituted or substitutedin the ortho, meta and para positions with C to C alkyl radicals, C to Calkoxy radicals, halogen, nitro, dimethylamino or sulfonamide.

6. The composition of claim 1 wherein the R radical is selected from thegroup consisting of phenyl, p-methoxyphenyl, p-chlorophenyl,m-nitrophenyl, p-(aminosulfonyl) phenyl, 3,5-dibromophenyl, 4- phenyl)phenyl, 4-(phenoxy) phenyl, p-(phenyl dimethyl silyl)phenyl,3,4-(methylenedioxy) phenyl, p-(methylthio) phenyl, p-toluyl, p(4-phenyl-n-butyl) phenyl, p-(dimethylamino) phenyl and 3,5-dimethylphenyland wherein the R radical is hydrogen.

References Cited UNITED STATES PATENTS 4/1966 Bean, Jr., et a1. 260-597/1967 Tocker 260-843 US. Cl. X.R.

